<!DOCTYPE html>
<title>Node.moveBefore should not preserve CSS transition state when crossing document boundaries</title>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>

<body>
  <iframe id="iframe">
  </iframe>
  <section id="new-parent">
  </section>
  <style id="style">
    #item {
      width: 100px;
      height: 100px;
      background: green;
      transition: left 10s;
      position: absolute;
      left: 0;
    }

    section {
      position: relative;
    }

    body {
      margin-left: 0;
    }
  </style>
  <script>
    promise_test(async t => {
      const iframe = document.querySelector("#iframe");
      const style = document.querySelector("#style");
      iframe.contentDocument.head.append(style.cloneNode(true));
      const item = iframe.contentDocument.createElement("div");
      item.id = "item";
      iframe.contentDocument.body.append(item);
      assert_equals(item.getBoundingClientRect().x, 0);
      item.style.left = "400px";
      await new Promise(resolve => item.addEventListener("transitionstart", resolve));

      // Calling `moveBefore()` on a cross-document element undergoing a
      // transition does not move the element, nor alter the transition.
      assert_throws_dom("HIERARCHY_REQUEST_ERR", () => {
        document.querySelector("#new-parent").moveBefore(item, null);
      });

      await new Promise(resolve => requestAnimationFrame(() => resolve()));
      assert_less_than(item.getBoundingClientRect().x, 20);
    }, "Moving a transition across documents should reset its state");
  </script>
</body>
